Electric heating unit.



C. S. STEWARD.

ELEGTRIC HEATING UNIT.

APPLICATION FILED NOV. 12, 1913.

Patented Feb. 17, 1914.

qmitnewm I face adapts for use in provided upon opposite sides withtrunmons UNITED STATES PATENT OFFICE.

OLAIENCE S. STIWARD, 0F CHATTANOOGA,'

ELECTRIC H EATING UNIT.

Specification of Letters 2mm. P tented Feb, 1'7, 1914.

12, 1918. Serial (L 800,827.

To all whom it may concern: a

Be it known that I, CLARENCE S. STEWARD, a citizen of the United States,residing at Chattanooga, in the county of Hamilton and State ofTennessee, have invented certain new and useful Improvements in ElectricHeating Units; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will. enableothers skilled in the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and tothealettersand figures of reference marked thereon, which form a part ofthis specification. f

This invention relates to certain new and useful. improvements inheating units for electric heaters and it has for its object theprovision of a unit of this character constructed of suitablenoncombustible insulating material of any desired shape and having oneof its faces provided with grooves disposes in parallel relationship,the said grooves being wider at the bottom than at the top and beingdesigned to receive a resistance wire, either coiled or in other form,the portion of the groove receiving-the wire being of greaterdiameterthan the width of 'the slot ilrthe surface. of the unitso'that theresistance wire will at all times be retained against possibleaccidental displacement.

The invention has for a further object the provision of a heat unit ofthe character described in which theresistance wire is so disto affordthe greatest possible efiiciency 1n givin of heat direct radiation andim rt tions 0 the p ate interposed between t e resistance coils, whichrtions are brought into direct contact with the article to' be heated.

A further objectof the invention resides inthefprovision of a heat unitof the characterdescribed which is imperforate and in which meang isprovided for. detachably securing the resistance wire without the use ofplates, bolts, screws or ozher mechanism which is not embraced in thconstructionof. the device itself and in which the rear face of the unitpresents a-uniforml smooth surto be used as a griddle, suitable bakingcakes, etc., the unit being which permit the unit to be lifted fromposition and reversed so that its cooking surface eat to the overhanginporcan be brought into position for use incookclosed through thetrunnions as the unitis removed or replaced.

A further and essential object of the inventlon consists in theprovision of a unit of secure a combination by means of which it ispossible to heat any vessel or article when the same is placed upon theunit by means of the radiation fromthe wireand by concom osed.

. hile I have shown in heat unit circular in form, it will at once beevident that, if desired, it may be rectangular or other preferredshape, the unit being preferably constructed of steatite or soapstone,as the character of this material is such as to best adapt it for thepurpose. To these ends and to such others as the inventlon may pertain,the same consists in the novel construction of the heat unit and in thepee lliar arrangement, combination and adaptation of parts, all as willbe more fully hereinafter described, shown in the accompanying drawingsand then specifically defined in the appended claims.

The invention is clearly illustrated in the accompanying, drawings,which, with the numerals of reference marked thereon,- form a art ofthis specification and in.wli1ch:-

embodying the features of my invention. Fi 2 is a section upon line 2-2of Fig. 1, an Fig. 3 is a detail sectional -view taken-on line 33 ofFig. 1. i

Reference now being had to the details of the I drawings by numeral, 1desi ates a disk, constructed preferably of steat te, soapstone, orother noncombustible material adapted for the purpose. Disposed atintervals, and extending transversely acrm one face of the disk is aseries of parallel grooves 2, 2. These grooves are open at their endsand have theirlower portions milled to form an enlarged .part 3 for thein ose of receiving the resistance wire 4.

acli alternate end of each of the bars 5, separatin the slots 2, is cutaway as shown at 6, 6, -t said cut away portions 6' being provided witha lug or stop 7, the upper face of which stop is disposed above thehorizontal plane taken through the lower surface of the bottom of theslots.

ing, the electric circuit. being opened .or'

the character described so constructed as to tact with the material ofwhich the nnit is the drawings a igure 1 is a top plan view of a heatunit end was attached.

It will be observed that the resistance wire t comprises a singlecontinuously Wound wire having its ends secured to the trunnions 8,8 bymeans of suitable binding screws 9. By the construction described, itwill be seen that the seatin of the wire within the slots is readily eected by first attaching an end of the wire to the trunnion upon oneside thence, when the Wire is carried to the open end of the slots atthe termination of the bar separating the first and second slots, it maybe bentaround the bar separating said" slots and is then carried to theopposite end where the depressed portion 6 admits of the wire beingcarried around into the next'succeeding slot and thence alternatelycarried from oneeslot to another by means of the open spaces 6 which areprovided at the ends of each alternate set of slots. \Vhen thus threadedand in place, the opposite end of the wire is clamped to the trunnionupon, the side of the unit opposite to that at which the first It willbe seen that, when the resistance wire is-thus seated within the slotsprovided for its reception, it

will be effectually protected or locked in position against accidentaldisplacement and will at all times be retained below the' sur-. face ofthe disk, while the overhanging edges of the bars separating the slotswill form a means for quickly receiving heat from the Wires and transmitthe same to the body of the bars. It will also be noted that in theconstruction which I have described the disk is imperforate, no meansbeing required for placing or retaining the resistance wire in position,other than that provided in-the construction of'the unit itself and itwill be further noted that by this construction the face of the unitopposite that which is provided with the slots carrying the resistancewires, being imperforate, forms a smooth and uniform surfaceadapted foruse for cooking purposes. \Vhen the unit is designed for heatingpurposes, these trunnions are placed within their bearings, which areprovided with means whereoy a current is established with the wire.vWhen itiis desired to reverse the plate so as to present its rear face,it is simply necessa to lift the unit from its bearings and, a terreversing it, to again restore the trunnions to their ournal bearingswhen the current will be reestablished and the heat imparted by thewires will be transmitted to the'disk. It will be noted that inreversing the plate, the wires will be at all times securely retainedwithin the slots in which they are seated and that no provisionwhatever, Otherthan described, will be re quired inorder to retain thewires in place. Having thus described my invention,

same comprising an imperforate body portion or a disk having chamberswithin the body portion thereof, said chambers being arranged inparallel relation and of a size and form adapted for the reception of aresistance wire, a series of open slots arranged in parallelrelationship with the chambers, said unit being so constructed that it.ma be reversed in position so as to present eit ier a uniform surface orthe chambered surface, substantially as shown and described.

SJA reversible heating unit for electric heaters, the 'samecomprising,in combina tion, an lmperforate dlsk having incorporated thereln aseries of chambers adapted to receive a resistance wire, said chambersbeing separated by bars integral with the disk, the edges of the barsoverhanging the wire receiving chambers, each alternate bar being cutaway to form open slots, said chambers being provided with wireretaining lugs, means upon opposite sides of the unit for securing theends of the wire, and means substantially as described for automatically making and breaking the circuit and communicating,

in reversing the unit, substantially as shown and described.

4. A heating unit for electric heaters, the same comprising animperforate body ortion or dlsk provided with a series 0 resistance wirechambers dis osed in parallel relationship and arranged low the surfaceof the disk, the said chambers being so disposed as to permit thecontinuous winding of a resistance wire throughout the series ofchambers, slots of less width than the width of-the chambers, said slotscommunicating with'the face of the disk, means integral with the bodyportion of the disk and below the surface thereof adapted, to preventthe movement of the wire in either direction within the chambers,substantially as shownvand described.

In testimony whereof I'hereunto afiixmy signature in presence of twowitnesses.

CLARENCE S. STEWARD.

Witnesses: I

A. FOWLER- 9 FRANKLIN H. Houom,

